Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of rotating turbine blades, and in some cases, such as aircraft, generate thrust for propulsion. Heavy frame gas turbines are also commonly used to drive electric generators for power generation.
Gas turbine engines are designed to operate at high temperatures to maximize engine efficiency, so cooling of certain engine components, such as a high pressure turbine and a low pressure turbine, can be beneficial. Typically, cooling is accomplished by ducting cooler air from high and/or low pressure compressors to the engine components that require cooling. Temperatures in the high pressure turbine can be 1000° C. to 2000° C. and the cooling air from the compressor can be 500° C. to 700° C., enough of a difference to cool the high pressure turbine.
Contemporary turbine blades, as well as vanes or nozzles, generally include one or more interior cooling circuits for routing the cooling air through the blade to cool different portions of the blade, and can include dedicated cooling circuits for cooling different portions of the blade, such as the leading edge, trailing edge and tip of the blade.
Turbine blade squealer tip rails in particular help to reduce aero losses and therefore increase the efficiency of turbine engines. The tip rail is subjected to a high heat loads and is difficult to effectively cool. It is frequently one of the hottest regions on the blade.